A research study in 1976 found Pulau Lima and its associated sea mounts as perhaps the most valuable entity within the Redang marine park as the reefs around this islet represented all environments found elsewhere in Redang, thereby providing a miniaturized view of the entire park's marine environment.
Easily accessible from the resorts at Pasir Panjang, Pulau Lima translated means 5 islets. There's good diving to be found all around it on the east, west, northern and southern tips. Among the most popular are Big Mount in the north and Black Coral Garden in the west with its large fields of anemone and other soft corals.
The southern tip of Pulau Lima comprises a series of large boulders covered with hard and soft corals, sea anemones, flamboyant nudibranchs and other invertebrates, with caves and grottos at the base of the boulders forming hideouts for many reef fishes. Coral encrusted walls sloping down to 30m can be explored on the eastern side, where morays and black tip sharks maybe observed. Sea fans and whips can be found at the deeper bottoms. Apart from the usual reef fishes, look out for lionfish and puffer fish.
In the northern side of Pulau Lima, "Big Mount", located about 50 to 100 metres from the northern tip of Pulau Lima, is considered by many divers to be the best of all the dive sites around Pulau Lima and is probably one of the deeper dive sites, going down to about 35 meters.
Highly rated by local divers, it provides interesting encounters with a variety of pelagics such as tuna, barracudas, groupers, black-tip sharks and the rare but unforgettable encounter with the whale shark. Starting at about 20 meters, the boulder terrain drops away to 30+ meters and is filled with many varieties of hard and soft corals, gorgonian fans, sea anemones and whip coral gardens.There are several dive sites around Pulau Lima (five islets), the most famous being "Big Mount". This is a submerged mount around 80 meters off the northern tip of the island; it is widely regarded as one of the best dive sites in the Redang Archipelago. The boulder formation drops down to around 30 meters and stronger currents can be present here hence the likelihood of seeing bigger pelagics. Mantas and whale sharks have been spotted here in the past.